Wheel thinning apparatus



Dec. 12, 1961 H. E. LUEBKEMANN 3,012,553

WHEEL. THINNING APPARATUS 3 Sheets-Sheet 1 Filed June 25, 1959 Dec. 12, 1961 H. E. LUEBKEMANN 3,012,553

WHEEL THINNING APPARATUS INVEN'TOR. HRRY E. l. UEBKEMINN Dec. 12, 1961 H. E. LUEBKEMANN l3,012,553

WHEEL THINNING APPARATUS Filed June 25. 1959 3 Sheets-Sheet 3 YIIIIIIIII.

INVENToR. 'H HAR/eYLZLz/Ea/EMQNN Ute The present invention relates to an apparatus for thinning a grinding Wheel.

In many applications it is desirable to have the workpiece engaging periphery of the grinding wheel a width different from the standard commercially available widths. In these cases it is necessary to thin the outer margin of a standard wheel to form the periphery to desired width. Heretofore this has been accomplished by engaging a forming tool with one side of the grinding wheel, at the outer margin, as the wheel rotates to cut away one corner of the wheel until the periphery reaches the desired size.

It has been found, however, particularly with ythin wheels, that unless relatively light cuts are taken, there is a tendency for the thinned portion of the wheel to break under the shearing force applied thereto through the tool before the desired periphery width is reached. In the present invention there is provided apparatus which substantially reduces this tendency for breakage and which is, therefore, particularly suitable for thinning relatively thin wheels. In brief, instead of using oneforming tool, a pair of forming tools straddling the outer margin of the wheel are utilized. These forming tools, ywhich may, for example be diamond points, simultaneously engage opposite sides of the wheels so ythat the shearing force transmitted through one diamond point to the margin of the wheel opposes the shearing force transmitted by the other diamond point to the wheel. With these forces opposing each other, the net shearing 'forcetransmitted to the margin is zero, or nearly zero, regardless of the forces applied through the individual tools and substantially deeper cuts can be taken than was `heretofore possible.

It is therefore an object of thepresent invention to provide an improved apparatus for thinning a grinding wheel which reduces the tendency for Wheel breakage during the thinning operation.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the Vscope of the appended claims, without departing from lor exceeding the spirit of the invention.

In the drawings:

FIG. -1 is an elevational front view of the apparatus of the present invention with the front of the `housing thereof removed;

FIG. 2 is a view taken on line 2-2 of FIG. l;

FIG. 3 is a view taken online 3-3 of FIG. 1;

FIG. 4 is a view taken on line 4-4 of FIG. l; and

FIG. 5 is a schematic representation illustrating the operation of the device of the present invention.

In FIGS. 1 and 2 the wheel thinning device 10 of the present invention is shown mounted on a grinding machine connected to the .Wheelhead housing 11 thereof. The device is contained in a housing 12 suspended m ce over the grinding wheel 13 of the machine. The wheel 13 is rotatably driven by spindle 14 mounted in the wheelhead for rotation about axis A.

Support member 15, in the form of a male dovetail, is connected to the front of wheelhead housing 11 by bolts (not shown) and constitutes a xed support for mounting the vertically movable slide support 16. The slide support 16 has a recess 17 (see FIG. 4) to receive the xed dovetail support, the recess having a locating shoulder 18 on one side and a gib 19 on the opposite side. The gib is carried in the slide support 16 by two screws 20 and -21 threadedly received in the slide support and received at one end in the gib. The screw 20vhas a knob 22 outside the slide support by which the gib can be tightened against the dovetail to clamp the slide support in selected positions on the xed support.

The slide support 16 has a threaded shaft 25Y1eceived therein and terminating in a knob 26 above thehousing Y12. A stud 27 screwed into the lixed support 15' lies in the path of shaft 25 and defines a stop member which, when engaged by the lower end of the shaft, locates the slide support vertically relative to the Xed support. The shaft 25 is vertically adjusted relative Vto the slide support by rotation of the knob 26. 'Ihree pins 28 are loosely received in holes in the fixed `support 15 and pass through a top plate *29V of the slide support 16 which extends over the rear edge thereof. Springs 30 are received over the4 pins `28 and are compressed between the fixed support 15 and top plate 29 of the slide support to partially counterbalance the weight of the slide support.

At the bottom the slide support 16 is 4c ut away at 35 to define two legs 36 and 37 to which are connected by screws (not shown) a front plate 38 and a rear plate 39;. The front plate and rear plates have slots 38a and V39a in their Ylower margins to receive the outer margin `13g: of thekgrinding wheel. As shown best in FIG. 3 a pair of shafts 40 and 41 are mounted in the plates 348' and 39 by bearings 42 for rotation about their central longitulinal axes B and C. Behind the rear plate 39 the shafts terminate in lhubs 43 and 44 and in front of lthe plate 38 receive collars 45 and 46. The collars .are held on the shafts, with the inner faces of the hubs and collars engaged with bearings 42, by means of the screws `-4,7 threadedly received in the shafts andhaving washers 4.8 engaged with the outer faces of the collars. Collar 1,6 is keyed to ,shaft 41 by pin 49' which extends radially from the collar. Spaced stop pins 66 and .67 are mounted in the front plate 38 to engage pin 49 and limit V the rota; tion of shaft 41.

Sleeves and 51 are pinned vto the shafts 40 and 41 respectively, at 52. Integral with sleeves 50 and 5.1 are the gears 53 and 54 which are aligned with Veach other between plates 38 and 39. Between and above the gea'fzs 53 and 54, and engaged therewith between 4the plates 38 and 39, are the gears 55 and 56 mounted onvstub shafts 57 and 58 in bearings 59 ,carried by r,the front and vrear plates. f

The gears v53, V55, 56 and 54 deflnea geartrain.which interconnects the hubs 43 and 44 for rotation in opposite directions. The hubs have tool carriers 6 0 and 61 in which are mounted diamond points 62 and 6.3 securedv by set screws 64,'to Vextend from the hubs. The `diamond points are synchronized through the gear train to `swing in always opposed relation relative to theplane R of the grinding wheel which passes between the diamond points.Y

In other words, the longitudinal axes of the diamond points D and E, regardless of their rotated positions, are always at equal but opposite angles to the plane of the grinding wheel. The gear train is operatively connected to lever 65, mounted in and extending from collar 46, for rotation of the hubs and hence the diamond points.

The device of the present invention may, if desired, be permanently mounted on a machine tool for use Whenever a forming of the wheel is required to produce or maintain a workpiece engaging periphery of required span. In the embodiment shown, the device 10 is mounted on the front of the wheelhead housing for convenience and consequently is forward of the axis A of the grinding wheel, as shown best in FIG. 2. When appropriately positioned vertically the diamond points swing in a circular arc and cut a circular recess out of the corners of the wheel in the vertical plane through the diamond points and the wheel. Thus, in a plane through the center of the wheel the sides of the recess will be elliptical. However, the periphery of the wheel can be formed to a desired span whether the sides of the recess are circular or elliptical and it is immaterial whether the device is aligned so the diamond points swing in a plane passing through the center of the wheel or passing through the wheel elsewhere.

The operation of the device of the present invention is best illustrated in FIG. 5.` As there shown the diamond points 62 and 63 lie on the axes D and E and swing about points on lines W and X, the lines straddling the plane R of the grinding wheel 13. For the initial cut the diamond points 62 and 63 are swung from points P and Q, which lie on line L parallel to the axis of the grinding wheel, through arcs S and T intersecting opposite corners U and V on the outer margin of the grinding wheel. The diamond points are synchronized in their movement so that they are at all times in opposed relation relative to the wheel. After the first cut the tools 62 and 63 are shifted along lines W and X for swinging about points indicated at P1 and Q1, respectively, in arcs S1 and T1. In a similar manner the forming tools are shifted in successive discrete amounts for swinging about successive diierent pairs of points, one on line W and the other on line X, each of said pairs of points lying on a line parallel to the axis of the grinding wheel and successively closer thereto whereby successive cuts are taken on the corners U and V of the Wheel. Preferably the lines W and X are at equal angles (in this case zero degrees) to the plane of the grinding wheel. When swung from their final positions at, say, points P2-Q2 the diamond points, swinging in arcs S2 and T2, intersect the workpiece engaging periphery Z of the wheel at points Z1 and Z2 which are spaced apart an amount Y equal to the desired span of the periphery.

In the operation of the device 10, when it is desired to form the outer margin of the wheel 13 to produce a workpiece engaging periphery Z of predetermined span Y, the clamping screw 20 is loosened so the slide support 16 will be free to drop downwardly on the fixed dovetail support 15. The screw 2S is rotated by knob 26 so the stop member 27 will hold the slide support 16 at a vertical position where the axes D and E of diamond points 62 and 63 pass through points corresponding to points P and Q of FIG. 5. The screw 20 is tightened to lock the slide in this position and the lever 65 is swung in one direction to take an initial cut on the corners of the wheel and in the opposite direction to return the lever to its initial position. The screw 20 is then loosened and screw 25, which serves as an adjustable stop member, is rotated to move the axes D and E to positions Where they pass through points corresponding to points P1 and Q1 of FIG. 5. The slide support is again clamped and another cut 1s taken on the corners of the Wheel. Successive cuts as required are similarly taken until the workpiece engaglng periphery Z is of the desired span. During all the cuts .the diamond points are moving in always opposed relation so that the component of fQrCe normal t the plane of the wheel transmitted through one of the damond points is balanced by an equal component of force acting in the opposite direction transmitted by the other diamond point. Thus, despite the depth of each cut, at no time is there a net shearing force (that is, a net force acting parallel to the axis A of the wheel) transmitted to the thin margin of the wheel and therefore the tendency for breakage is substantially reduced.

After the final cut has been taken the slide support can be quickly elevated by raising knob 26 (as indicated in dotted lines) and the slide can be clamped in the raised position until again required. When so raised trip member 68 connected to the slide member 16 operates switch 69 connected to the housing 12. The switch may be connected in the circuit of the machine so that the normal feeding cycle thereof is possible only when the switch is operated. After the wheel has worn so that the span Y is greater than desired, the device 10 is again utilized to reduce the periphery to the desired size. As shown in dotted lines in FIG. 2 the slide 16 can be lowered substantially to accommodate wheels of reduced diameter.

In the claims:

1. A device for mounting adjacent a grinding wheel to thin the workpiece engaging periphery thereof comprising a fixed support, a slide support having a pair of shafts mounted thereon for rotation about spaced axes xed on the slide support, said slide support mounted on the fixed support for movement normal to the grinding wheel axis towards and away from the grinding wheel with the shafts thereof straddling the plane of the grinding wheel, a stop member on at least one of said supports to stop movement of the slide support toward the grinding wheel at a rst selected position, said stop member adjustable to permit incremental advance of the slide support to successive selected positions, means to clamp the slide support to the fixed support in said selected positions, a diamond point extending from each shaft for swinging upon rotation of the shaft in an arc intersecting the corner of the wheel in an amount determined by the selected position of the slide support, a continuous gear train interconnecting said shafts for rotation thereof in opposite directions with the diamond points synchronized to engage the -grinding wheel simultaneously and swing across the opposite corners thereof in opposed relation, and a lever operatively connected to said gear train to rotate said shafts.

2. In a grinding machine having a grinding wheel mounted thereon to rotate in a plane, a fixed support mounted adjacent the grinding wheel, a slide support having a pair of shafts mounted thereon for rotation about spaced axes, said slide support mounted on the txed support for movement towards and away from the grinding wheel with the shafts thereof straddling the plane of the grinding wheel, a stop member connected to one of said supports and a rotatable shaft threadedly received in the other of said supports for selective positioning of the slide support relative to the grinding wheel, means to clamp the slide support in selected positions, a diamond point extending from each shaft for swinging upon rotation of the shaft in an arc intersecting the corner of the wheel in varying amounts according to the selected position of the slide support, a gear train interconnecting said shafts for rotation thereof in opposite directions with the diamond points synchronized to engage the grinding wheel simultaneously and swing across the opposite corners thereof in opposed relation, and a lever operatively con nected to said gear train to rotate said shafts.

3. In a machine tool having a grinding wheel rotatable on an axis in a plane, a device to thin the workpiece engaging periphery of the grinding wheel comprising a fixed support adjacent the grinding wheel, a slide support mounted on the fixed support for movement in a direction normal to the axis of the wheel, a pair of forming tools mounted on the slide support for rotation about axes xed in spaced apart relation on the slide support and in 6 straddling relation to the plane of the grinding wheel, a References Cited in the file of this patent continuous gear train mounted on the slide support inter- UNITED STATES PATENTS connecting said forming tools for rotation thereof in opposite directions with the forming tools synchronized to Y 1,729,460 Slocum Sept- 24, 1929 engage the grinding wheel simultaneously and swing across 5 FOREIGN PATENTS the opposite corners thereof in opposed relation, means to drive said gear train, and means to regulate movement 37,161 Sweden F611 3, 1912 of the slide support on the xed support. 192,588 Great Britain Feb. 8, 1923 

